1. Field of the Invention
The invention generally relates to a pixel structure, and more particularly, to a pixel structure capable of improving display quality.
2. Description of Related Art
The rapid development of multi-media comes mostly as a result of the recent advance in the production of semiconductor devices and display apparatus. Liquid crystal display, with its high display quality, good spatial utilization, low power consumption and radiation-free operation, has gradually become the mainstream display product in the market. To provide better display quality to the liquid crystal display, all kinds of wide viewing angle liquid crystal displays have been developed. The most common ones include, for example, the in-plane switching (IPS) liquid crystal display, the fringe field switching liquid crystal display, the multi-domain vertical alignment (MVA) liquid crystal display and so on.
FIG. 1 is a schematic cross-sectional view of a conventional pixel structure. As shown in FIG. 1, the conventional pixel structure 100 includes a substrate 112, a thin film transistor T, a capacitor-coupling electrode 118c, a first pixel electrode 119a, a second pixel electrode 119b and an alignment film PI. The thin film transistor T mainly includes a gate 114, a gate insulating layer 116, a semiconductor layer 117, a source 118a and a drain 118b. In FIG. 1, the thin film transistor T is a bottom gate structure, and the thin film transistor T is covered by the passivation layer 120. More specifically, the thin film transistor T is disposed on the substrate 112, and the capacitor-coupling electrode 118c is electrically connected to the drain 118b of the thin film transistor T. In addition, the first pixel electrode 119a is electrically connected to the drain 118b of the thin film transistor T, and the capacitor-coupling electrode 118c is located between the second pixel electrode 119b and the substrate 112.
In an ideal condition, the first pixel electrode 119a is electrically insulated from the second pixel electrode 119b, and the second pixel electrode 119b is coupled to the capacitor-coupling electrode 118c underneath. In other words, after turning on the active device T, the first pixel electrode 119a and the second pixel electrode 119b can have different voltages so that the liquid crystals (not shown) corresponding to the first pixel electrode 119a and the second pixel electrode 119b can have different inclining states. It should be noted that residual charges on the second pixel electrode 119b and the alignment film PI are difficult to remove because the second pixel electrode 119b is in a floating state. Consequently, the performance of the second pixel electrode 119b will be affected by the residual charges so that the problem of having a residual image in the next display picture needs to be solved.